Mitochondrial Politics: "3 Parent Baby" issue before FDA

This week the FDA examines the "3 Parent Baby" methods, which insert mitochondrial DNA from a third individual into the mother's egg, according to Dina Fine Maron for Scientific American.

The idea arose as a method to increase fertility in mothers with high risk factors for certain mitochondrial diseases and allow their children to be unaffected.  

When most people think of genes, they think of DNA packed within the nucleus that gives rise to proteins that help cells, and in turn, organisms, function. But the cell's genome also contains DNA that associates with other organelles and are passed from generation to generation by cytoplasmic inheritance, particularly in the mitochondria.

In nature, the offspring inherit 100% of their mitochondrial DNA from their mother's egg, since the fertilized egg contains the mother's cytoplasm and organelles.

This image, borrowed from the Nature Education website shows the transmission of mitochondrial DNA from mother to zygote (offspring). The chloroplasts and mitochondria are crossed out in the father's gamete because they are not transmitted. Only the father's nucleus fertilizes the egg.

These mitochondrial diseases, which can include loss of vision, seizures, or premature death "occur in about one in every 5,000 live births and are incurable," according to the Scientific American.

The FDA's approval would permit clinical trials to be run.

Some find that these "3 Parent Babies" may be a cure for infertility, or an increase in the quality of life for offspring, but others see it as a landmark for genetic engineering, and a bad one at that, according to CNN's article "FDA considering '3-parent babies'." 

Magnetosomes transformed, giving organisms and research new directions

Researchers at Albert Ludwigs University of Freiburg transformed a non-magnetic bacteria line with genes for magnetosomes, organelles that sense and respond to the earth's magnetic field, according to Phys.org.

This image, taken from boundless.com, shows a magnetosome in a bacterial cell. Each of the black dots is a magnetic crystal structure. 

Crystal structures inside the magnetosomes act like a compass needle together, thereby navigating the cell along with Earth's magneticism, a process called magnetotaxis.

The paper, Biosynthesis of magnetic nanostructures in a foreign organism by transfer of bacterial magnetosome gene clusters, published by nature.com, explains that the researchers were able to transcribe the  30 gene section of the bacterial genome that encodes for the magnetosensitivity. 

The scientists would like to analyze the set of genes to come up with minimal sets of genes with normal functionality to look at the necessity and evolution of the complex magnetosome. 

An Organelle as Part of a System: Chromatin

Researchers in Edinburgh have presented a quantitative, statistics-based approach to organelle proteonomics, the study of proteins, according to Genome Web. 

The paper, "Proteomics of a fuzzy organelle: interphase chromatin," published on the 17, discusses methods for looking at chromatin, in context, without separating the parts.

Chromatin is the organelle comprised of DNA, histone proteins, and  cofactors present in the nucleus of a cell.

This image from the Molecular Expressions Cell Biology and Microscopy site shows chromatin in its tangled form within the nucleus and stretched out and isolated.

The paper discusses methods to look at not just the DNA, which is often isolated for sequencing studies, but to examine the complex itself and how the components interact with one another. 

This may be another step to understanding the complex functionality of chromatin, and may set an example for other studies, looking at DNA in context, as a 3-D structure with a function dependent on interactions, rather than as a one dimensional piece of isolated information. 

Penn State researchers operate nanomotors in HeLa cells

A team of chemists and engineers at Penn State have been able to insert and control nanomotors within human cells, according to  Krista Weidner for PennStateSCIENCE.

The gold nanoparticles were successfully inserted into live HeLa cells, cervical cancer cells derived from those taken from Henrietta Lacks in 1951.

The chemists were able to use ultrasound pulses to control the nanomotors, according to Weidner's report. These pulses help move and rotate the motors around cell structures.

This video was taken of the nanomotors, also called nanorods, inside the HeLa cells.

 

These molecular motors may have implications not just for diagnosing cellular diseases, but possibly for helping repair cell problems from within. 

Like the HeLa cells they were first used in, scientists can only speculate what contributions the nanomotors will make in biochemistry.

An Organelle's Help in Dinosaur Puzzle

Forms of the melanosome organelle suggest colored, iridescent feathers, were present in dinosaur-era birds, according to an article by Thomas Carannant on the Science World Report website.

The birds of the dinosaur era were previously thought to have little color variation, according to an older (2011) National Geographic article. 

Melanosomes produce and transport melanin, a pigment that gives animal cells color and protects them from the sun.

Carannant explains that the shapes of the melanosomes recently analyzed from fossils resemble those that are known to produce brown, black and gray pigments in modern bird lineages and also cause iridescence. This suggests that the feathered Amniota emerged around the same evolutionary era, during the age of Dinosaurs.  

Photo credit: Li, et al (original article from Nature Magazine), "Melanosome diversity across Amniota." The tree diagram at the bottom shows the proposed evolutionary relationships while the scatter plots show the observed patterns in size (diameters and lengths).

  
The tree of life is revised again, thanks to an organelle. The question remains whether this fits in with most of the accepted taxonomy or changes it completely. 

The Tea Lover's Organelle: Tannosome

A team of French and Hungarian scientists identified an organelle responsible for producing the chemical that gives tea, wine, and unripe fruit a bitter flavor according to Scientific American's blogger Jennifer Frazer.

The tannosome produces tannins, the bitter chemicals that enhances flavor but deter many herbivores. Tannin denatures proteins in the herbivore, making it difficult for the animal to process its food and produce energy at a regular rate. For more information on tannins specifically, see this explanation of the biotoxins from Cornell.

Previously, scientists assumed that the rough endoplasmic reticulum produced the tannins, which were then stored in the vacuoles. Instead, the team found that they are produced within the chloroplasts, and stored in special vesicles  called tonoplasts that prevent the chemicals from disintegrating their own cell's proteins.

Photo credit: Jean-Marc Brillouet, et al. (from the original research paper in the Annals of Botany).
The new process, proposed by the researchers, suggests that tannosomes are found within the inner membrane of the vascular plants' chloroplasts. The tannosomes make the tannins, which are then shuttled by a vesicle into the vacuole where they are stored inside a tonoplast, which separates them from the other contents of the vacuole.

Since organelles are useful in separating biological processes, it is not entirely surprising that tannins require their own production centers. It is worth noting that even the collection of organelles may still increase as scientists turn their attention to new processes and chemicals.